From a7f775428b8f5808815c0e3004020cedb94cbe3b Mon Sep 17 00:00:00 2001 From: Al Viro Date: Sat, 27 Feb 2016 19:31:01 -0500 Subject: [PATCH] should_follow_link(): validate ->d_seq after having decided to follow ... otherwise d_is_symlink() above might have nothing to do with the inode value we've got. Cc: stable@vger.kernel.org # v4.2+ Signed-off-by: Al Viro --- fs/namei.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/fs/namei.c b/fs/namei.c index e0881c0b..65a0e9d 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1712,6 +1712,11 @@ static inline int should_follow_link(struct nameidata *nd, struct path *link, return 0; if (!follow) return 0; + /* make sure that d_is_symlink above matches inode */ + if (nd->flags & LOOKUP_RCU) { + if (read_seqcount_retry(&link->dentry->d_seq, seq)) + return -ECHILD; + } return pick_link(nd, link, inode, seq); } -- 2.7.4